Kelly bushing



Dec. 2, 1952 A. l.. STONE 2,520,133

KELLY BUSHING Filed Dec. 22, 1948 3 sheets-sheet 2 53 FIG. 4.

Jl l

Patented Dec. 2, 1952 KELLY BUsHING I Albert L. Stone, Redondo Beach, Calif., assignor, by mesne assignments, to Standard Oil Development Company, Elizabeth, N. J.,

l tion of Delaware a corpora- Application December 22, 1948,Serial N o. 66,772 i l This invention relates to rotary drilling apparatus and more particularly toa drive bushing for a Kelly rod.

In the drilling of oil `wells b y the rotary drilling method, it is common practice to4 employ a suspended string of drillpipe at the lower end of which a drill bit is positioned and-at the upper end of which a drill stringdriving mechanism, such as a Kelly bar, is attached. The Kelly bar is usually square or polygonal in cross section, although it may be circular in cross section and provided with longitudinally extending ilutes or grooves. The Kelly bar passes through a Kelly bar bushingr mounted in the rotary table which is adapted to be rotated. The Kelly bar is rotated by the Kelly bar bushing on rotation of the rotary table and is adapted to move longitudinally through the said bushing. When rotating the drill stem by the aforementioned means, torques of high magnitude are imposed on the Kelly bar by the bushing and, consequently, large amounts offriction ar set up between the Kelly bar and the bushing. Frictional resistance to the longitudinal movement of theKelly Vbar through the bushing is greatly aggravated byv conditions `which are often encountered in actual drilling operations such as misalignment of the Kelly bar with the axis of the borehole or a slight bend 'inthe Kelly bar. As a matter of fact, an overall bend of as little as 11g of an inch may produce such great resistance to the longitudinal movement of the kelly through the bushing as to prohibit its passage therethrough.

Various expedients have been provided for reducing the resistance of the Kelly bar bushing Vto longitudinal movement of the kelly thereagainst the bushing caused by resistance of bit rotation under power of the rotary blade. This battering not only causes wear but also may deform the Kelly bar.-

Still other efforts directed toward reducing the resistance ofhthe Kelly'bar bushing* to longitudinal movement of the kelly therethrough have involved the provision `of rollers in the bushing itself. These rollers are rotatably mounted on axles and are positioned inthe central passage lpf.` the bushing. so that A.eachroller mayY rotate 1 Claim. (Cl. 255-23) on its axle with its outersurface inline contact with a surface of the polygonal Kelly bar. Normally a suicient number of rollers are provided so that each surface of the Kellybar is in contact with at least one roller. Vhen' such bushings are new, they offer little resistance to longitudinal movement of the Kellybar but as the rollers and their axles become worn, the line contact between the outer surface of fthe rollers and the surface vof the Kelly bar tends t'o become a point contact, the, point of contact tending to "shift more and more toward the leading' edgeof the surface contacted by the roller and toward anedge of the roller. This tendency, once it lhas started, continues at an accelerated'pace inasmuch as the torque exerted on the Kelly bar bythe rollers is applied over a continually diminishing area of contact. A point may bereache'd when the Kelly bar is so seriously deformed and the rollers and their axles so badly worn that longitudinal movementof the Kelly bar through the bushing is effectively prohibited.`

It is the principal object ofthe present invention to provide 4a Kelly bar bushing which will permit rotative movement to be imparted to the kelly and which will also permit the kelly to move longitudinally therethrough While being rotated even when thekelly' is misaligned with the boreholel or when'the' kelly is bent. IAnother object of the presentinvention is to provide a Kelly bar bushing in which the forces tending to rotate the'Kelly bar are evenly distributed along the bar and which 'oifers a'minimum vof 'resistance to the longitudinal'movement.ofthe kelly therethrough while the kelly is rotated. A further object is to provide 'a Kelly bar bushing' carrying anti-friction elements which will" provide a constant area of contact withthe Kelly bar and which will not tendto causeappreciable deformation of the kelly. v

The present Vinvention contemplates the use `of either'a Kelly bar of circular cross' section having longitudinally extending grooves on its o-uter surlface or a conventional polygonal Kelly bar. In

lplane parallel to the axis of the central passage 3 of the bushing. This arrangement permits the rotative movement of the rotary table to be transmitted through the balls to the Kelly bar while permitting the kelly to move longitudinally through the bushing in contact with the balls.

A preferred form of my invention contemplates that the balls will be disposed in a mass of deformable material, such as rubber, so as to permit the bushing to absorb the misalignment forces in drilling operations, such for example, as misalignment produced by off-center suspension of the Kelly bar or misalignment due to a bent Kelly bar. The deformable material employed is preferably so arranged as to be in tension rather than in compression so that the bushing will automatically return to its proper alignment with the axis of the bore-hole after the forces tending to misalign the bushing elements cease to operate thereon.

The present invention is more fully illustrated in the accompanying drawings in which:

Fig. l is a vertical section through a drill rotating mechanism equipped with a round grooved kelly and a drive bushing embodying the features of the present invention; y

Fig. 2 is a section through the' drive bushing and kelly taken on the line II-f -II of Fig. l;

Fig. 3 is a vertical section of a modified form of the Kelly drive bushing of my invention;

Fig. 4 is a section through the driveA bushing and kelly taken on the line IV- IV of Fig. 3;

Fig. 5 is a vertical section of a mo'diiied form of the drive bushing of the present invention adapted to be employed with a Kelly rod having polygonal cross section; and

Fig. 6 is a section through the drive bushing and kelly taken on the line VI'VI of Fig. 5

Referring to the drawing, and more particularly to Figs. l and 2, I indicates a portion of a typical rotary table having the usual central opening II. The upper portion' off central opening is polygonal in cross section, preferably square, and defines seat lI3 for receiving a Kelly bar bushing. Numeral Il designatesvthe body or housing of the Kelly bar bushing with which the present invention is concerned. The outer vertical surface of ,housing I I is normally cylindrical Vfor a major portion of its height while the lower end thereof is conventionally polygonal in cross section, normally square, and adapted to fit slidably in central opening and to rest on shoulder I3. H ousing I4 defines a central passage substantially circular in cross section deiining spaced keyways I5 opening into said passageway. Disposed in central passage |5 and spaced away from keyways I6 are a plurality of raceway housing members Il. Each of raceway housing members I'I defines an arcuate surface I8 substantially equidistant from the center of opening I5, members I1 being so arranged that surfaces I thereof cooperate to define a substantially cylindrical centralpassage having its axis substantially coincident with the axis of central opening |5. Keys 9 are adapted to fit slidably into keyways I6 and project inwardly from the inner surface of housing M toward the center of central opening I5.

Each racewayvhousing member Il defines a raceway 2| lwhich carries disposed therein circulating balls 22. Raceway 2| is disposed in raceway housing member I 'l in such manner that the balls 22 in circulating therein travel in a plane which passes through the longitudinal axis of the central passage 'formed by surfaces I8 of raceway housing members I1. 'Raceway 2| consists of substantially parallel linear sections 23 and 2A and substantially circular upper section 25 and substantially circular lower section 26, all of said sections being in communication to form one continuous raceway of uniform diameter. Section 24 of raceway 2| for at least a portion of its length forms an open slot in surface I8 of such width that circulating balls 22 are held within raceway 2| While at least a. portion of the balls circulating in said portion of the raceway extends slightly beyond arcuate surfaces I8 to project into the central passage formed by surfaces I8. The portion of balls 22 extending into this central passage engages with the longitudinally extending grooves 28 carried by the outer surface of Kelly bar 29. In Fig. 1 seven balls 22 are shown in engagement with grooves 28 of Kelly bar 29. Preferably, raceway 2| contains sufcient balls 22 to occupy all of the space defined by raceway 2| except for a small space, as at 30, in section 25 of the raceway. The purpose of providing a free space in raceway 2| is to permit the free rotation of balls 22 in travelling the path dei-ined by raceway 2|. With this arrangement each of balls 22 is in contact with two adjacentballs except when negotiating the space in section 25 indicated by numeral 30, in which case the two balls at the top of the race, that is, the two balls on each sideof space 30, are in contact with only one other ball. The provision of space 30 minimizes the tendency of balls 22 to jam in their circulation within race 2| when Kelly bar 2 9 is moved longitudinally through the bushing assembly while being rotated.

Raceway housing members I1 and keys I9 are 'bonded together in driving relation by means of a deformable bonding material 20 such as natural or synthetic rubber. The bonding of raceway members I'I and keys I9 may be accomplished by placing raceway housing members I`| and keys I9 in proper relation in .a mold having an inner surface shaped similarly to the inner surface of housing I4 andl filling the space in the mold between members Il and keys I9 with deformable bonding material. The deformable bonding material may be then vulcanized to the surfaces of members |'I and keys I9. In accomplishing the molding operation raceway housing members may be arranged equidistant from the center of a central opening by arranging said members radially around a mandrel having a diameter somewhat smaller than the diameter of the kelly to be fitted by the completed assembly. 'Ihe diiference in diameter between the mandrel and the kelly to be fitted will be determined by the -amount of pre-loading desired between balls 22 vand kelly 2S when the completed bushing is mounted on the kelly-.

l It will be understood from Fig. 2 and from the previous description that the molding oper'- ation is conductedin 'such a manner that deformable material 2U will be positioned between the outer edges of raceway housing members I1 and housing I4 The deformable material located inthis space will be in compression and consequently the completed assembly will be able to withstand very large misalignment loads. It will be further understood;however,` that the aforedescribed molding operation may be so conducted that no deformable material 20 is present between the outer edge of ball raceway housing members I'l and housing I4, reliance in absorbing misalignmentloads being placed entirely upon the extensive bond between deformable material 20 and raceway housing members I 1 and between deformable material 20 and keys I9. When the mold is made in this last mentioned manner, the mass of deformable material 20 between keys I9 and raceway housing members I'I is in tension and shear, -rather than in compression, thus providing a maximum of shock absorption.

While Figs. 1 and 2 show three raceway housing members I'I and three longitudinally extending grooves 28 in kelly 29, it will be understood that a grooved round kelly having a larger number of longitudinally extending grooves 28 may be employed with a bushing assembly having only three raceway housing members I'I. In any event, raceway housing members I'I are arranged in housing I4 and deformable material 20 so that the balls 22 carried by members I'I operatively engage in three of grooves 28. It will be further understood that a larger number than three raceway housing members I'I may be employed. For example, it might be desirable to employ as many as six such members II with a grooved kelly 29 having at least six longitudinally extending grooves 28. Preferably, of course, raceway housing members I'I are radially spaced within housing I4 and in any event must be spaced so that the balls 22 carried by members I'I will engage with longitudinally extending grooves 28 of Kelly bar 29. It will be further understood that as few as two raceway housing members I1 may be employed although I prefer to employ at least three such members.

It will also be noted from Figs. l and 2 and from the previous description that deformable material 20 may be molded in such a way as to contact the outer surfaces of kelly 29. It should be mentioned that deformable material 20 may instead be molded so that it does not Contact the outer surfaces of kelly 29, although I prefer that it contact the kelly. Contact between deformable material 20 and the outer surface of kelly 29 below housing members I'I affords a number of advantages, among which are the wiping effect which such contact provides. When contact is afforded, drilling uid is wiped off the kelly as it passes upwardly through the kelly drive bushing described, thereby reducing the amount of fluid which might possibly interfere with the circulation of balls 22 in raceways 2| and also reducing the wear of balls 22 and kelly 29.

While Fig. 1 shows raceway 2I to be oval in form and further shows seven balls 22 in contact with Kelly grooves 28, it will be understood that the raceway carried Iby raceway housing members Il may be circular in form and that raceway 2I may be so arranged that a larger or smaller number than seven balls 22 are continuously in contact with Kelly grooves 2B. The number of balls 22 carried by raceway 2I will be determined by the amount of force which the balls will be required to transmit and by the size of the balls employed. When it is expected that low torques will be encountered, raceway 2l may be so arranged that only one ball 22 is in contact with Kelly groove 28 at any instant of time, although I prefer to arrange raceway 2l so that at least two yballs. 22 are continuously in contact with Kelly grooves 28. Where it is expected that very high torques will be encountered, raceway 2l should be so arranged that a larger number of balls are continuously in contact with Kelly groove 28.

Having described the component parts of the embodiment of my invention shown in Figs. 1 and 2 and the relation of these parts to each other, its mode of operation will now be briefly CTI described. The molded assembly comprising housing member I1, keys I9 and deformable material 20 may be formed into the completed assembly in the following manner. A cone having a base whose diameter is approximately the same as the diameterof the lower end of the kelly may be placed on the lower end of the kelly with its base abutting against the lower end of the kelly and the molded assembly forced over the cone until balls 22 carried by raceway housing members I1 drop into Kelly bar grooves 28. Housing I4 may then be slipped over the molded assembly and the molded assembly held in place.-

in housing I4 by means of hold-down ring 3l which is adapted to be engaged with housing I4'y as by means of threads 32.

preventing the molded assembly including race way housing members II from moving from their' intended positions in housing I4. Kelly `bar 29,. together with the Kelly bar bushing of my inven-4 tion mounted thereon, is then hoisted by suitable: means, as by the drilling line of a drilling rig, and placed over the axis of the well. The Kellyv bar and the Kelly bar bushing are then lowered. until housing I4 is seated on shoulder I3 of rotary table I9. The Kelly bar and bushing are now in. operative relation with respect to rotary table I0. Rotation of rotary table Ill produces correspending rotation of the bushing of my invention. This rotative force is transmitted through deformable material 20 to balls 22 and, in turn, to Kelly bar 29. When Kelly bar 29 is moved longitudinally through the Kelly bar bushing of my invention, balls 22 circulate in raceway 2 I. It will be obvious that inasmuch as balls 22 are free to circulate in raceway 2l, the Kelly bar bushing of my inventori offers very little friotional resistance to the longitudinal passage of Kelly bar 29 through the said bushing while imparting rotative motion thereto.

Figs. 3 and 4 show another embodiment of the Kelly bar bushing of my invention. Referring to Figs. 3 and 4, 50 indicates a portion of a typical rotary table having the usual central opening 5I. The upper portion of central opening 5I is polygonal in cross section, normally square, and defines a seat 52 for receiving a Kelly bar bushing. Numeral 53 designates the body or housing of the Kelly bar bushing with which the present invention is concerned. The outer vertical surface of housing 53 may be cylindrical for a major portion of its height while the lower end thereof may be polygonal in cross section, preferably square, and adapted to t slidably in central opening 5I and to rest on shoulder 52. Housing 53 defines a central passage 54 and an inwardly extending shoulder 56 at the lower end thereof. Housing 53 also defines in its inner surface a plurality of radially spaced keyways 51 opening into central passage 54, surface 55 forming keyway 5`I being tapered downwardly and inwardly. A plurality of raceway housing members 58 defining outwardly extending keys 59 are disposed in central passage 54 with keys 5.9 engaged in keyways 5l. With raceway housing members so disposed the inner surfaces 59 of said members dei-lne a central passage 6I through which a Kelly bar 62 may be passed longitudinally. The axis of central passage BI is substantially coincident with the axis of the central passage defined by housing 53.

Each raceway housing member 59 defines a The downwardly projecting upper end 33 of ring 3I abuts against. surfaces 34 and 35 formed by an upper, outer portion of raceway housing members I'I, thus:

raceway 63 which carries disposed therein circulating balls 64. Raceway 63 is ,disposed in raceway housing member 58 in such manner that the balls 64 in circulating therein travel in a plane which passes through the longitudinal axis of the central passage formed by the inner surfaces 60 of raceway housing members 58. Raceway 63 is positioned in raceway housing members 58 so that at least for a portion of its length it forms an open slot in the inner surface 60 of the member, the slot being of such arrangement that balls 64 are held within raceway 63 while at least a portion of the balls circulating past the slot in raceway 63 extends slightly beyond the inner surface 60 of raceway housing members 58 to project into the central passage 6| formed by the said surfaces. The portion of the balls 64 extending into central passage 6| engages with the longitudinally extending grooves 65 of Kelly bar 62. Raceway housing members 53 are held against upward movement with respect to housing 53 by means of hold-down ring 66 which is adapted to be mechanically connected to housing 53, as by means of threads 61, ring 66 having a downwardly projecting portion which abuts against surfaces 68 and 69 of raceway housing members 58.

Having fully described the component parts of the embodiment of my invention shown in Figs. 3 and 4 and the relationship of these parts to each other, the mode of operation and use of this embodiment will now be briefly described. In assembling the Kelly drive bushing of my invention for use in rotating a grooved kelly, housing 53 may be placed in its conventional position in rotary table 50, that is, it may be seated on shoulder 52 of rotary table 56. Kelly bar 62 is then lowered into central opening 54 of housing 53 and suspended in said opening. Raceway housing members 53 are then individually lowered into central opening 54 of housing 53 with keys 59 in engagement with keyways 51. At the same time that keys 59 are engaged in keyways 51, that portion f balls 64 which projects through the slot formed by raceway 63 and the inner surface 60 of raceway housing member 58 is engaged with a longitudinally extending groove 6.5; of kelly 62. This operation is repeated with respect to each raceway housing member 56 until all of these members have been inserted. It will be understood that as few as two raceway housing members may be suitably employed for driving a grooved kelly. It will be further understood that these members must be positioned in housing 53 so that balls 64 carried by each of membersv 58 will engage with one longitudinally extending groove 65. Of course, Kelly bar 62 must be equipped with at least as many grooves 6,5 as the number of members 56 disposed in housing 53. After all of raceway housing members 5,8 have been inserted in housing 53, the said members are secured against upward movement in the said housing by hold-down ring 66.

While the Kelly bar bushing of my invention has heretofore been described and shown when used in conjunction with a longitudinally grooved Kelly bar of circular cross section, it will be understood that the Kelly bar bushing of myinvention may be modified so as to be suitable for use in conjunction with Kelly bars havinga polygonal cross section. Accordingly, an embodiment of my invention is shown in Figs. 5l and 6 which is adapted to be employed withA a kelly having a polygonal cross section. While the drawing shows, for the sake of simplicity, a square kelly,

it will be apparent that the Kelly bar bushing of my invention may be suitably `modified so as t0 be used with any Kelly bar having any polygonal cross section.

Referring now to Figs. 5 and 6, |00 indicates a portion of a typical rotary table having the usual central opening IBI. The upper portion of central opening |9| is polygonal in cross section, normally square, and defines a seat |02 for receiving a Kelly bar bushing. Numeral |63 designates the body or housing of the Kelly bar bushing with which the present invention is concerned. The outer vertical surface of housing |63 is normally cylindrical for a major portion of its height While the lower end thereof is conventionally polygonal in cross section, normally square, and adapted to fit slidably into central opening ||l| vand to rest on shoulder |92. Housing |63 defines a central passage |612 and inwardly extending shoulder |65 at the lower end thereof. Inner surface of housing |63 defines a plurality of circumferentially spaced recesses |66 with surface |06 of recess |68 tapering downwardly and inwardly from the upper end |01 of housing |03 to inwardly extending shoulder |65. A raceway housing member |69, defining a raceway ||6 carrying balls ||2, is disposed in each of recesses |63 and extends into central passage |63. Outer surface ||0 and side surfaces of each of raceway housing members |63 are arranged to t slidably in recess |63. Raceway housing members |69 are so arranged with respect to each other and with respect to the axis of central opening |94 that the circulating balls ||2 carried by each of raceway housing members |89 contact a longitudinal surface of polygonal Kelly bar ||3. Fig. 6 of the drawing shows that raceway housing members |69 are disposed within housing |63 in such manner that the plane passing through the circulating ball race I6 is substantially perpendicular to a surface |5 of Kelly bar I I3 when Kelly bar |3 is disposed in central opening |04.

Raceway ||6 is disposed in raceway housing member |99 in such manner that balls l2 in circulating in the said raceway travel in a vertical plane. Raceway H5 for a portion of its extent forms an open slot in surface ||1, the said slot being of such width that circulating balls 2 are held within raceway I6 while at least a portion of balls I2 in circulating in said portion of raceway ||6 project beyond surface ||1. This slot is of such length that at least a portion of balls |2 circulating in raceway |6 past the said slot contact Kelly bar H3. In Fig. 6 seven balls ||2 are shown as extending into central passage |64 and lin engagement with a longitudinally extending surface ||5 of kelly ||3 near the leading edge of said surface.

Raceway housing members |69 are held against upward movement with respect to housing |03 by means of hold-down ring 3 which is adapted to be mechanically connected to housing |63 by means of threads H3, ring H3 having a downwardly projecting portion |23 which abuts against surfaces |23 and |2| of raceway housing member |69.

While raceway housing members |69 are shown in Fig. 6 as being disposed within housing |03 in such manner that balls ||2 contact the leading edge of a longitudinally extending surface I|5 of kelly ||3, it will be understood that raceway housing members |69 may be disposed within housing |63 in such manner that balls ||2 contact a longitudinal surface of kelly |3 at a point other than the leading edges of the said surface.

I prefer, however, that raceway housing members |09 be so arranged within housing |03 that balls I I2 contact the leading edge of a surface of kelly I I3. It will also be noted from Fig. 6 that inner surface II'l of raceway housing member |69 may be so arranged that the portion of surface lll adjacent the trailing edge of a longitudinally extending surface H of kelly H3 does not project as far toward the center of central opening litri as that portion of surface II'I adjacent the leading edge of the said surface. This arrangement reduces the possibility of Kelly bar I i3 contasting any portion of raceway housing member 809 other than balls |I2.

When it is desired to employ the Kelly bar bushing of the embodiment shown in Figs. 5 and 6 for rotating a polygonal kelly, housing IBS is placed in operative position in rotary table |09 with its lower end abuttingl on shoulder |92. Kelly bar II3 is then suspended within housing |93 with its longitudinal axis aproximately in the center of central opening |64. Each of raceway housing members |09 is then individually inserted in housing |03 with surfaces I I0 and III thereof positioned in recess |08 and With balls I I2 in contact with a longitudinally extending surface of kelly ||3 as shown. After all of raceway housing members |09 have been inserted, they are held in position against upward movement with respect to housing |03 by means of holddown ring IIB.

Having described only typical preferred forms of my invention, I do not wish to be limited or restricted to the specic details herein set forth but wish to reserve to myself any variations or modications that may appear to those skilled in the art or fall within the scope of the following claim.

Having fully described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

A driving member vadapted to rotate an elongated drven member while permitting longitudinal movement of said elongated driven member therethrough comprising, in combination, a housing adapted to be rotated defining a central annulus and carrying keys projecting inwardly into said annulus, a plurality of raceway housing members radially disposed within said annulus 10 and radially spaced from said keys and said housing, each said raceway housing member defining an inner surface and having an endless raceway therein, deformable material vulcanized to said raceway housing members and said keys bonding said members and. said keys together in driving relation, the inner surfaces of said raceway housing members cooperating to denne a central passage within said central annulus, said raceway housing members being radially yieldable with respect to the axis of said central passage, each of the raceways in said raceway housing mem- .bers lying in a plane passing through said central passage and parallel to the axis of said central passage, each raceway opening for at least a portion of its extent into said central passage through said inner surface and balls disposed in each of said raceways for travel therein, the inner surface of said raceway housing members being so formed as to prevent the escape of the balls from said raceway, said balls partially projecting into said central passage when travelling past that portion of the raceway opening into said central passage and engaging with the elongated driven member, whereby rotation of the housing imparts corresponding rotation to the elongated driven member while permitting unlimited longitudinal movement of said elongated driven member through said central pasage.

ALBERT L. STONE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 702,509 Titus June 17, 1902 782,043 McCready Feb. 7, 1905 851,728 Bayrer Apr. 30, 1907 1,094,972 Bocorselski ..1 Apr. 28, 1914 1,918,108 Jonkhoff July 11, 1933 2,160,516 Pranger May 30, 1939 2,211,881 Collett et al Aug. 20, 1940 2,259,460 Dexter Oct. 21, 1941 FOREIGN PATENTS Number Country Date 125,573 Austria Nov. 25, 1931 

